Introduction

Approximately 3 to 5 percent of all pregnant women in the United States are diagnosed as having gestational diabetes. These women and their families have many questions about this disorder. Some of the most frequently asked questions are: What is gestational diabetes and how did I get it? How does it differ from other kinds of diabetes? Will it hurt my baby? Will my baby have diabetes? What can I do to control gestational diabetes? Will I need a special diet? Will gestational diabetes change the way or the time my baby is delivered? Will I have diabetes in the future?

This course will address these and many other questions about diet, exercise, measurement of blood sugar levels, and general medical and obstetric care of women with gestational diabetes. It must be emphasized that these are general guidelines and only  health care professional(s) can tailor a program specific to meet individual  needs.

What is gestational diabetes and what causes it?
Diabetes (actual name is diabetes mellitus) of any kind is a disorder that prevents the body from using food properly. Normally, the body gets its major source of energy from glucose, a simple sugar that comes from foods high in simple carbohydrates (e.g., table sugar or other sweeteners such as honey, molasses, jams, and jellies, soft drinks, and cookies), or from the breakdown of complex carbohydrates such as starches (e.g., bread, potatoes, and pasta). After sugars and starches are digested in the stomach, they enter the blood stream in the form of glucose* (figure 1). The glucose in the blood stream becomes a potential source of energy for the entire body, similar to the way in which gasoline in a service station pump is a potential source of energy for your car. But, just as someone must pump the gas into the car, the body requires some assistance to get glucose from the blood stream to the muscles and other tissues of the body. In the body, that assistance comes from a hormone called insulin. Insulin is manufactured by the pancreas, a gland that lies behind the stomach. Without insulin, glucose cannot get into the cells of the body where it is used as fuel. Instead, glucose accumulates in the blood to high levels and is excreted or “spilled” into the urine through the kidneys.

FIGURE 1
Insulin: The Key to Turning Food into Energy

* For the purpose of this course the words sugar and glucose are used synonymously.

When the pancreas of a child or young adult produces little or no insulin we call this condition juvenile­onset diabetes or Type I diabetes (insulin­dependent). Unlike women with Type I diabetes, women with gestational diabetes have plenty of insulin. In fact, they usually have more insulin in their blood than women who are not pregnant. However, the effect of their insulin is partially blocked by a variety of other hormones made in the placenta, a condition often called insulin resistance.

The placenta performs the task of supplying the growing fetus with nutrients and water from the mother's circulation. It also produces a variety of hormones vital to the preservation of the pregnancy. Ironically, several of these hormones such as estrogen, cortisol, and human placental lactogen (HPL) have a blocking effect on insulin, a “contra­insulin” effect. This contra­insulin effect usually begins about midway (20 to 24 weeks) through pregnancy. The larger the placenta grows, the more these hormones are produced, and the greater the insulin resistance becomes. In most women the pancreas is able to make additional insulin to overcome the insulin resistance. When the pancreas makes all the insulin it can and there still isn't enough to overcome the effect of the placenta's hormones, gestational diabetes results. If we could somehow remove all the placenta's hormones from the mother's blood, the condition would be remedied. This, in fact, usually happens following delivery.

How does gestational diabetes differ from other types of diabetes?
There are several different types of diabetes. Gestational diabetes begins during pregnancy and disappears following delivery. Another type is referred to as juvenile­onset diabetes (in children) or Type I (in young adults). These individuals usually develop their disease before age 20. People with Type I diabetes must take insulin by injection every day. Approximately 10 percent of all people with diabetes have Type I (also called insulin­dependent diabetes).

Type II diabetes or noninsulin­dependent diabetes (formerly called adult­onset diabetes) is also characterized by high blood sugar levels, but these patients are often obese and usually lack the classic symptoms (fatigue, thirst, frequent urination, and sudden weight loss) associated with Type I diabetes. Many of these individuals can control their blood sugar levels by following a careful diet and exercise program, by losing excess weight, or by taking oral medication. Some, but not all, need insulin. People with Type II diabetes account for roughly 90 percent of all diabetics.

Who is at risk for developing gestational diabetes and how is it detected?
Any woman might develop gestational diabetes during pregnancy. Some of the factors associated with women who have an increased risk are obesity; a family history of diabetes; having given birth previously to a very large infant, a stillbirth, or a child with a birth defect; or having too much amniotic fluid (polyhydramnios). Also, women who are older than 25 are at greater risk than younger individuals. Although a history of sugar in the urine is often included in the list of risk factors, this is not a reliable indicator of who will develop diabetes during pregnancy. Some pregnant women with perfectly normal blood sugar levels will occasionally have sugar detected in their urine.

The Council on Diabetes in Pregnancy of the American Diabetes Association strongly recommends that all pregnant women be screened for gestational diabetes. Several methods of screening exist. The most common is the 50­gram glucose screening test. No special preparation is necessary for this test, and there is no need to fast before the test. The test is performed by giving 50 grams of a glucose drink and then measuring the blood sugar level l­hour later. A woman with a blood sugar level of less than 140 milligrams per deciliter (mg/dl) at l­hour is presumed not to have gestational diabetes and requires no further testing. If the blood sugar level is greater than 140 mg/dl the test is considered abnormal or “positive:” Not all women with a positive screening test have diabetes. Consequently, a 3­hour glucose tolerance test must be performed to establish the diagnosis of gestational diabetes.

If the physician determines that the complete 3­hour glucose tolerance test be taken, the patient will be asked to follow some special instructions in preparation for the test. For 3 days before the test, eat a diet that contains at least 150 grams of carbohydrates each day. This can be accomplished by including one cup of pasta, two servings of fruit, four slices of bread, and three glasses of milk every day. For 10 to 14 hours before the test the patient should not eat and not drink anything but water. The test is usually done in the morning in the physician's office or in a laboratory. First, a blood sample will be drawn to measure fasting blood sugar level. Then the patient will be asked to drink a full bottle of a glucose drink (100 grams). This glucose drink is extremely sweet and occasionally makes some people feel nauseated. Finally, blood samples will be drawn every hour for 3 hours after the glucose drink has been consumed. The normal values for this test are shown in table 1.


TABLE 1. 3­Hour Glucose Tolerance Test for Gestational Diabetes

	Diagnostic Criteria	Normal Mean Values*
	Blood Glucose Level	Blood Glucose Level
Fasting	105 mg/dl	80 mg/dl
I hour	190 mg/dl	120 mg/dl
2 hour	165 mg/dl	105 mg/dl
3 hour	145 mg/dl	90mg/dl

From 752 Unselected Pregnancies

If two or more blood sugar levels are higher than the diagnostic criteria, the patient has gestational diabetes. This testing is usually performed at the end of the second or the beginning of the third trimester (between the 24th and 28th weeks of pregnancy) when insulin resistance usually begins. If the patient had gestational diabetes in a previous pregnancy or there is some reason why the physician is unusually concerned about the risk of developing gestational diabetes, the 50­gram glucose screening test may be taken as early as the first trimester (before the 13th week). Remember, merely having sugar in urine or even having an abnormal blood sugar on the 50­gram glucose screening test does not necessarily mean the patient has gestational diabetes. The 3­hour glucose tolerance test must be abnormal before the diagnosis is made.

How does gestational diabetes affect pregnancy and will it hurt the baby?
The complications of gestational diabetes are manageable and preventable. The key to prevention is careful control of blood sugar levels just as soon as the diagnosis of gestational diabetes is made.

One should be reassured that there are certain things gestational diabetes does not usually cause. Unlike Type I diabetes, gestational diabetes generally does not cause birth defects. For the most part, birth defects originate sometime during the first trimester (before the 13th week) of pregnancy. The insulin resistance from the contra­insulin hormones produced by the placenta does not usually occur until approximately the 24th week. Therefore, women with gestational diabetes generally have normal blood sugar levels during the critical first trimester.

*O'Sullivan, J. B. Establishing Criteria for Gestational Diabetes. Diabetes Care 3: 437­439, 1980.



FIGURE 2
The Role of High Maternal Glucose in Fetal Macrosomia

One of the major problems a woman with gestational diabetes faces is a condition the baby may develop called “macrosomia.” Macrosomia means “large body” and refers to a baby that is considerably larger than normal. All of the nutrients the fetus receives come directly from the mother's blood (figure 2). If the maternal blood has too much glucose, the pancreas of the fetus senses the high glucose levels and produces more insulin in an attempt to use the glucose. The fetus converts the extra glucose to fat. Even when the mother has gestational diabetes, the fetus is able to produce all the insulin it needs. The combination of high blood glucose levels from the mother and high insulin levels in the fetus results in large deposits of fat which causes the fetus to grow excessively large, a condition known as macrosomia. Occasionally, the baby grows too large to be delivered through the vagina and a cesarean delivery becomes necessary. The obstetrician can often determine if the fetus is macrosomic by doing a physical examination. However, in many cases a special test called an ultrasound is used to measure the size of the fetus. This and other special tests will be discussed later.

In addition to macrosomia, gestational diabetes increases the risk of hypoglycemia (low blood sugar) in the baby immediately after delivery. This problem occurs if the mother's blood sugar levels have been consistently high causing the fetus to have a high level of insulin in its circulation. After delivery the baby continues to have a high insulin level, but it no longer has the high level of sugar from its mother, resulting in the newborn's blood sugar level becoming very low. The baby's blood sugar level will be checked in the newborn nursery and if the level is too low, it may be necessary to give the baby glucose intravenously. Infants of mothers with gestational diabetes are also vulnerable to several other chemical imbalances such as low serum calcium and low serum magnesium levels.

All of these are manageable and preventable problems. The key to prevention is careful control of blood sugar levels in the mother just as soon as the diagnosis of gestational diabetes is made. By maintaining normal blood sugar levels, it is less likely that a fetus will develop macrosomia, hypoglycemia, or other chemical abnormalities.

What can be done to reduce problems associated with gestational diabetes?
In addition to obstetricians, there are other health professionals who specialize in the management of diabetes during pregnancy including internists or diabetologists, registered dietitians, qualified nutritionists, and diabetes educators. A doctor may recommend that the patient see one or more of these specialists during  pregnancy. In addition, a neonatologist (a doctor who specializes in the care of newborn infants) should also be called in to manage any complications the baby might develop after delivery.

One of the essential components in the care of a woman with gestational diabetes is a diet specifically tailored to provide adequate nutrition to meet the needs of the mother and the growing fetus. At the same time the diet has to be planned in such a way as to keep blood glucose levels in the normal range (60 to 120 mg/dl). Specific details about diet during pregnancy are discussed later.

An obstetrician, diabetes educator, or other health care practitioner can teach the patient how to measure her own blood glucose levels at home to see if levels remain in an acceptable range on the prescribed diet. The ability of patients to determine their own blood sugar levels with easy­to­use equipment represents a major milestone in the management of diabetes, especially during pregnancy. The technique called “self blood glucose monitoring” (discussed in detail later) allows one to check her blood sugar levels at home or at work without costly and time­consuming visits to the doctor. The values of one's blood sugar levels also determine if one needs to begin insulin therapy sometime during pregnancy. Short of frequent trips to a laboratory, this is the only way to see if blood glucose levels remain under good control.

Glucose Monitoring

What is self blood glucose monitoring?
Once  diagnosed as having gestational diabetes, the patient and health care providers will want to know more about day-to-day blood sugar levels. It is important to know how exercise habits and eating patterns affect blood sugars. Also, as pregnancy progresses, the placenta will release more of the hormones that work against insulin. Testing of blood sugar level at important times during the day will help determine if proper diet and weight gain have kept blood sugar levels normal or if extra insulin is needed to help keep the fetus protected.

Self blood glucose monitoring is done by using a special device to obtain a drop of  blood and test it for blood sugar level. The doctor or other health care provider should fully explain the procedure to the patient. Make sure that she is shown how to do the testing before attempting it on her own. Some items she may use to monitor blood sugar levels are:

Lancet–a disposable, sharp needle-like sticker for pricking the finger to obtain a drop of blood.
Lancet device–a spring­loaded finger sticking device.
Test strip–a chemically treated strip to which a drop of blood is applied.
Color chart–a chart used to compare against the color on the test strip for blood sugar level.
Glucose meter–a device which “reads” the test strip and gives you a digital number value.


How often and when should the patient test?
She may need to test her blood several times a day. Generally, these times are fasting (first thing in the morning before you eat) and 2 hours after each meal. Occasionally, she may need to test more frequently during the day or at night.

How should she record her test results?
Most manufacturers of glucose testing products provide a record diary, although some health care providers may have their own version.

She should record any test result immediately because it's easy to forget what the reading was during the course of a busy day. She should always have this diary with her when she visits her doctor or other health care provider or when she contacts them by phone. These results are very important in making decisions about  health care.

Are there any other tests ?
In addition to blood testing, she may be asked to check her urine for ketones. Ketones are by-products of the breakdown of fat and may be found in the blood and urine as a result of inadequate insulin or from inadequate calories in her diet. Although it is not known whether or not small amounts of ketones can harm the fetus, when large amounts of ketones are present they are accompanied by a blood condition, acidosis, which is known to harm the fetus. To be on the safe side, she should watch for them in her urine and report any positive results to her doctor.

How to test for ketones?
To test the urine for ketones, she can use a test strip similar to the one used for testing  blood. This test strip has a special chemically treated pad to detect ketones in the urine. Testing is done by passing the test strip through the stream of urine or dipping the strip in and out of urine in a container. As  pregnancy progresses, she might find it easier to use the container method. All test strips are disposable and can be used only once. This applies to blood sugar test strips also. Don't use  blood sugar test strips for urine testing, and you cannot use your urine ketone test strips for blood sugar testing.

When to test for ketones?
Overnight is the longest fasting period, so the patient should test her urine first thing in the morning every day and any time her  blood sugar level goes over 240 mg/dl on the blood glucose test. It is also important to test if she becomes ill and is eating less food than normal.

Is it ever necessary to take insulin?
Yes, despite careful attention to diet some women's blood sugars do not stay within an acceptable range. A pregnant woman free of gestational diabetes rarely has a blood glucose level that exceeds 100 mg/dl in the morning before breakfast (fasting) or 2 hours after a meal. The optimum goal for a gestational diabetic is blood sugar levels that are the same as those of a woman without diabetes.

There is no absolute blood sugar level that necessitates beginning insulin injections. However, many physicians begin insulin if the fasting sugar exceeds 105 mg/dl or if the level 2 hours after a meal exceeds 120 mg/dl on two separate occasions. Blood sugar levels measured at home will help the doctor know when it is necessary to begin insulin. The ability to perform self blood glucose monitoring has made it possible to begin insulin therapy at the earliest sign of high sugar levels, thereby preventing the fetus from being exposed to high levels of glucose from the mother's blood.

Will the baby be healthy?
The ultimate concern of any expectant mother is, “Will my baby be all right?” There is an array of simple, safe tests used to assess the condition of the fetus before birth and these can be particularly valuable during a pregnancy complicated by gestational diabetes. Tests that may be given during  pregnancy include:

Ultrasound.
Ultrasound uses short pulses of high­frequency, low­intensity sound waves to create images. Unlike x-rays, there is no radiation exposure to the fetus. First used during World War II to detect enemy submarines below the surface of the water, ultrasound has since been used safely in obstetrics. Occasionally, the date of her last menstrual period is not sufficient to determine a due date. Ultrasound can provide an accurate gestational age and due date that may be very important if it is necessary to induce labor early or perform a cesarean delivery. Ultrasound can also be used to determine the position of the placenta if it is necessary to perform an amniocentesis (another test discussed later).

Fetal movement records.
Recording fetal movement is a test to help determine the condition of the baby. Fetal activity is generally a reassuring sign of well-being. Women are often asked to count fetal movements regularly during the last trimester of pregnancy. She may be asked to set aside specific times to lie down on her back or side and count the number of times the baby moves or kicks. Three or more movements in a 2-hour period is considered normal.

Fetal monitoring.
Modern instruments make it possible to monitor the baby's heart rate before delivery. Currently, there are two types of fetal monitors — internal and external. The internal monitor consists of a small wire electrode attached directly to the scalp of the fetus after the membranes have ruptured. The external monitor uses transducers secured to the mother's abdomen by an elastic belt. One transducer records the baby's heart rate by a sensitive microphone called a doppler. The other transducer measures the firmness of the abdomen during a contraction of the uterus. It is a crude measure of the strength and frequency of contractions. Fetal monitoring is the basis for the non-stress test and the oxytocin challenge test described below.

Non-stress test.
The “non­stress” test refers to the fact that no medication is given to the mother to cause movement of the fetus or contraction of the uterus. It is often used to confirm the well-being of the fetus based on the principle that a healthy fetus will demonstrate an acceleration in its heart rate following movement. Fetal activity may be spontaneous or induced by external manipulation such as rubbing the mother's abdomen or making a loud noise above the abdomen with a special device. When movement of the fetus is noted, a recording of the fetal heart rate is made. If the heart rate goes up, the test is normal. If the heart rate does not accelerate, the fetus may merely be “sleeping”; if, after stimulation, the fetus still does not react, it may be necessary to perform a “stress test” (oxytocin challenge test).

Stress test (oxytocin challenge test).
Labor represents a stress to the fetus. Every time the uterus contracts, the fetus is momentarily deprived of its usual blood supply and oxygen. This is not a problem for most babies. However, some babies are not healthy enough to handle the stress and demonstrate an abnormal heart rate pattern. This test is often done if the non-stress test is abnormal. It involves giving the hormone oxytocin (secreted by every mother when normal labor begins) to the mother to stimulate uterine contractions. The contractions are a challenge to the baby, similar to the challenge of normal labor. If the baby's heart rate slows down rather than speeds up after a contraction, the baby may be in jeopardy. The stress test is considered more accurate than the non­stress test. Nevertheless, it is not 100 percent fool­proof and the obstetrician may want to repeat it on another occasion to ensure its accuracy. Most women describe this test as mildly uncomfortable but not painful.

Amniocentesis.
Amniocentesis is a method of removing a small amount of fluid from the amniotic sac for analysis. Either the fluid itself or the cells shed by the fetus into the fluid can be studied. In mid­pregnancy the cells in amniotic fluid can be analyzed for genetic abnormalities such as Down syndrome. Many women over the age of 35 have amniocentesis for just this reason. Another important use for amniocentesis late in pregnancy is to study the fluid itself to determine if the lungs of the fetus are mature and able to withstand early delivery This information can be very important in deciding the best time for a woman with Type I diabetes to deliver. It is not done as frequently to women with gestational diabetes.

Amniocentesis can be performed in an obstetrician's office or on an outpatient basis in a hospital. For genetic testing, amniocentesis is usually performed around the 16th week when the placenta and fetus can be located easily with ultrasound and a needle can be inserted safely into the amniotic sac. The overall complication rate for amniocentesis is less than 1 percent. The risk is even lower during the third trimester when the amniotic sac is larger and easily identifiable.

Does gestational diabetes affect labor and delivery?
Most women with gestational diabetes can complete pregnancy and begin labor naturally. Any pregnant woman has a slight chance (about 5 percent) of developing preclampsia (toxemia), a sudden onset of high blood pressure associated with protein in the urine, occurring late in pregnancy. If preclampsia develops, the obstetrician may recommend an early delivery. When an early delivery is anticipated, an amniocentesis is usually performed to assess the maturity of the baby's lungs.

Gestational diabetes, by itself, is not an indication to perform a cesarean delivery, but sometimes there are other reasons the doctor may elect to do a cesarean. For example, the baby may be too large (macrosomic) to deliver vaginally, or the baby may be in distress and unable to withstand vaginal delivery.

Careful control of blood sugar levels remains important even during labor. If a mother's blood sugar level becomes elevated during labor, the baby's blood sugar level will also become elevated. High blood sugars in the mother produce high insulin levels in the baby. Immediately after delivery high insulin levels in the baby can drive its blood sugar level very low since it will no longer have the high sugar concentration from its mother's blood.

Women whose gestational diabetes does not require that they take insulin during their pregnancy, will not need to take insulin during their labor or delivery. On the other hand, a woman who does require insulin during pregnancy may be given insulin by injection on the morning labor begins, or in some instances, it may be given intravenously throughout labor. For most women with gestational diabetes there is no need for insulin after the baby is born and blood sugar level returns to normal immediately. The reason for this sudden return to normal lies in the fact that when the placenta is removed the hormones it was producing (which caused the insulin resistance) are also removed. Thus, the mother's insulin is permitted to work normally without resistance. The doctor may want to check  blood sugar level the next morning, but it will most likely be normal.

Should I expect my baby to have any problems?
One of the most frequently asked questions is, “Will my baby have diabetes?” Almost universally the answer is no. However, the baby is at risk for developing Type II diabetes later in life, and of having other problems related to gestational diabetes, such as hypoglycemia (low blood sugar) mentioned earlier. If  blood sugars were not elevated during the 24 hours before delivery, there is a good chance that hypoglycemia will not be a problem for the baby. Nevertheless, a neonatologist (a doctor who specializes in the care of newborn infants) or other doctor should check the baby's blood sugar level and give extra glucose if necessary.

Another problem that may develop in the infant of a mother with gestational diabetes is jaundice. Jaundice occurs when extra red blood cells in the baby's circulation are destroyed, releasing a substance called bilirubin. Bilirubin is a pigment that causes a yellow discoloration of the skin (jaundice). A minor degree of jaundice is common in many newborns. However, the presence of large amounts of bilirubin in the baby's system can be harmful and requires placing the baby under special lights which help get rid of the pigment. In extreme cases, blood transfusions may be necessary.

Will the patient develop diabetes in the future?
For most women gestational diabetes disappears immediately after delivery. However, blood sugars should be checked after the baby is born to make sure  levels have returned to normal. Women who had gestational diabetes during one pregnancy are at greater risk of developing it in a subsequent pregnancy. It is important to have appropriate screening tests for gestational diabetes during future pregnancies as early as the first trimester.

Pregnancy is a kind of “stress test” that often predicts future diabetic problems. In one large study more than one­half of all women who had gestational diabetes developed overt Type II diabetes within 15 years of pregnancy. Because of the risk of developing Type II diabetes in the future, the patient should have her blood sugar level checked during routine check­ups. There is a good chance the patient will be able to reduce the risk of developing diabetes later in life by maintaining an ideal body weight and exercising regularly.

Diet & Weight Gain

Why is a special diet recommended?
A nutritionally balanced diet is always essential to maintaining a healthy mother and successful pregnancy. The foods chosen become the nutrient building blocks for the growth of the fetus. For a woman with gestational diabetes, proper diet alone often keeps blood sugar levels in the normal range and is generally the first step to follow before resorting to insulin injections. Careful attention should be paid to the total calories eaten daily, to avoid foods which increase blood sugar levels, and to emphasize the use of foods which help the body maintain a normal blood sugar. A registered dietitian is the best person to help with meal planning to meet  individual needs.

How much weight should be gained?
Of all questions asked by pregnant women, this is the most common. The answer is particularly important for women with gestational diabetes. The weight that is gained is a rough indication of how much nutrition is available to the fetus for growth. An inadequate weight gain may result in a small baby who lacks protective calorie reserves at birth. This baby may have more illness during the first year of life. An excessive weight gain during pregnancy, however, has an insulin­resistant effect, just like the hormones produced by the placenta, and will make the blood sugar level higher.

The “optimal” weight to gain depends on the weight  before becoming pregnant. Pre-pregnancy weight is also a rough indication of how well-nourished the patient is before becoming pregnant. If  at a desirable weight for body size before she become pregnant, a weight gain of 24 to 27 pounds is recommended. If  approximately 20 pounds or more above desirable weight before pregnancy, a weight gain of 24 pounds is recommended. Many overweight women, however, have healthy babies and gain only 20 pounds. If one becomes pregnant when  underweight, there is a need to gain more weight during the pregnancy to give the baby the extra nutrition he or she needs for the first year. A gain 28 to 36 pounds, depending on how underweight the patient is before becoming pregnant. Table 3 shows whether  pre-pregnancy weight is considered underweight, normal weight, or overweight. A nutrition advisor or health care provider can recommend an appropriate weight gain. How weight gain is distributed is illustrated in figure 3.

TABLE 3. Pre­Pregnancy Weight
Use this chart to determine if pre­pregnancy weight is normal, underweight, or overweight.

*Normal weight for “thin-boned” women will be closer to the lower end of this range. For “big-boned” women, it will be closer to the higher end.

Total recommended weight gain is often not as helpful as a weekly rate of gain. Most women gain 3 to 5 pounds during the first trimester (first 3 months) of pregnancy. During the second and third trimesters, a good rate of weight gain is about three­quarters of a pound to one pound per week. Gaining too much weight (2 or more pounds per week) results in putting on too much body fat. This extra body fat produces an insulin-resistant effect which requires the body to produce more insulin to keep blood sugar levels normal. An inability to produce more insulin, as in gestational diabetes, causes  blood sugar levels to rise above acceptable levels. If weight gain has been excessive, often limiting weight gain to approximately three-quarters of a pound per week (3 pounds per month) can return blood sugar levels to normal. Fetal growth and development depend on proper nourishment and will be placed at risk by drastically reducing calories. However, one can limit weight gain by cutting back on excessive calories and by eating a nutritionally-sound diet that meets the patient's needs and the needs of her baby. Remember that dieting and severely cutting back on weight gain may increase the risk of delivering prematurely. If blood sugar levels continue to go up and she is not gaining excessive weight or eating improperly, the safest therapy for the well-being of the fetus is insulin.

Occasionally,  weight may go up rapidly in the last trimester (after 28 weeks) and there may be an increase in water retention, such as swelling in the feet, fingers, and face. If there is any question as to whether the rapid weight gain is due to eating too many calories or too much water retention, keeping records of how much food is eaten and exercise patterns at this time will be very helpful.  By examining the Food and Exercise Record Sheet, a nutrition advisor can help determine which is causing the rapid weight gain. In addition, by examining  legs and body for signs of fluid retention, the physician can help determine the cause of your weight gain. If  weight gain is due to water retention, cutting back drastically on calories may actually cause more fluid retention. Bed rest and resting on the side will help  to lose the build-up of fluid. Limit intake of salt (sodium chloride) and very salty foods, as they tend to contribute to water retention.

Marked fluid retention when combined with an increase in blood pressure and possibly protein in the urine are the symptoms of preeclampsia. This is a disorder of pregnancy that can be harmful to both the mother and baby. The patient should inform the obstetrician of any rapid weight gain, especially if eating moderately and gaining more than 2 pounds per week. Should the patient  develop preeclampsia, she should be especially careful to eat a well-balanced diet with adequate calories.

After being diagnosed as having gestational diabetes, many women notice a slower weight gain as they start cutting the various sources of sugar out of their diet. This seems to be harmless and lasts only I or 2 weeks. It may be that sweets were contributing a substantial amount of calories to the diet.





How should she eat during her pregnancy?
As with any pregnancy, it is important to eat the proper foods to meet the nutritional needs of the mother and fetus. An additional goal for women with gestational diabetes is to maintain a proper diet to keep blood sugars as normal as possible.



TABLE 4. Protein Equivalents

The daily need for calories increases by 300 calories during the second and third trimesters of pregnancy. If non­pregnant calorie intake was 1800 calories per day and weight gain was maintained, a calorie intake of 2100 calories per day is usual from 14 weeks until delivery. This is the equivalent of an additional 8 ounce glass of 2milk and one­half of a sandwich (1 slice of bread, approximately 1 ounce of meat, and I teaspoon of margarine, mayonnaise, etc.) per day. The need for protein also increases during pregnancy. Make sure diet includes foods high in protein, but not high in fat (table 4). Most vitamins and minerals are also needed in larger amounts during pregnancy. This can be attained by increasing dairy products, especially those low in fat, and making sure to include whole grain cereals and breads, as well as fruits and vegetables in the diet each day. To make sure to get enough folate (a B vitamin critical during pregnancy) and iron, the obstetrician will usually recommend a prenatal vitamin. Prenatal vitamins do not replace a good diet; they merely help  to get the nutrients we need. To absorb the most iron from prenatal vitamin, take it at night before going to bed, or in the morning on an empty stomach.

The Daily Food Guide (table 5) serves as a guideline for food sources that provide important vitamins and minerals, as well as carbohydrates, protein, and fiber during pregnancy. The recommended minimal servings per day appear in parenthesis after each food group listed. This guide emphasizes foods that are low in fat and in sugar (discussed later).


TABLE 5. Daily Food Guide (Each item equals one serving)

1/4 cup cooked barley

1/4 cup peanuts

Exercise

Should the patient exercise?
A daily exercise program is an important part of a healthy pregnancy. Daily exercise helps one feel better and reduces stress. In addition, being physically fit protects against back pain, and maintains muscle tone, strength, and endurance. For women with gestational diabetes, exercise is especially important.

Regular exercise increases the efficiency or potency of the body's own insulin. This may allow one to keep blood sugar levels in the normal range while using less insulin.

Moderate exercise also helps blunt appetite, helping to keep weight gain down to normal levels. Maintaining the correct weight gain is very important in preventing high blood sugar levels.

Generally, one can continue any exercise program or sport  participated in prior to pregnancy. Caution, however, should be used and  sports or exercises where one might fall, or that involve jolting should be avoided. Pre-pregnancy bicycling, jogging, and cross-country skiing are good exercises to continue during pregnancy.

Vigorous walking is good for women who need to start exercising and have not been active before pregnancy.

Exercising frequently, 4 to 5 days per week, is necessary to get the “blood sugar lowering” advantages of an exercise program. A warm­up period of 5 to 10 minutes and a cool-down period of 5 to 10 minutes is important. Always stop exercising if one feels pain, dizziness, shortness of breath, faintness, palpitations, back or pelvic pain, or experience vaginal bleeding. Also, avoid vigorous exercise in hot, humid weather or if  a fever is present. It is important to prevent dehydration during exercise, especially during pregnancy. The American College of Obstetricians and Gynecologists (ACOG) recommends drinking fluids prior to and after exercise, and if necessary, during the activity to prevent dehydration.

An ACOG report* issued in 1985, warned that target heart rates for pregnant and postpartum women should be set approximately 25 to 30 percent lower than rates for non-pregnant women. It may be that exercising too vigorously will direct blood flow away from the uterus and fetus. ACOG recommends that pregnant women measure their heart rate during activity and that maternal heart rate not exceed 140 beats per minute.

Because both insulin and exercise lower blood sugar levels, the combination can result in hypoglycemia or low blood sugar One needs to be aware that this is a potential problem, and should be familiar with the symptoms of hypoglycemia (confusion, extreme hunger, blurry vision, shakiness, sweating). When exercising, take along sugar in the form of hard, sugar-sweetened candies just in case blood sugar becomes too low. When on insulin, one should always carry some form of sugar for potential episodes of hypoglycemia.

It may be necessary to eat small snacks between meals if the exercise results in low blood sugar levels.

One serving of fruit will keep blood sugars normal for most short­term activities (approximately 30 minutes).

One serving of fruit plus a serving of starch will be enough for activities that last longer (60 minutes or more).

If exercising right after a meal, the snack should be eaten after the exercise. If the exercise is 2 hours or more after a meal, the snack should be eaten before the exercise.

*Home Exercise Program: Exercise During Pregnancy and the Postnatal Period. American College of Obstetricians and Gynecologists May 1985 6 pp.


What happens if diet and exercise fail to control blood sugars?
If  blood sugars tend to go over the acceptable levels (105 mg/dl or below for fasting, 120 mg/dl or below 2 hours after a meal) one may need to take insulin injections. Insulin is a protein and would be digested like any other protein in food if it were given orally. The needles used to inject insulin are extremely fine, so there is little discomfort. If insulin injections are necessary, the patient needs to be taught how to fill the syringe and how to do the injections herself.

It is very likely that the amount or dosage of insulin needed to keep  levels of blood sugar normal will increase as  pregnancy advances. This does not mean  gestational diabetes is getting worse. As any healthy pregnancy progresses, the placenta will grow and produce progressively higher levels of contra-insulin hormones. As a result one will likely need to inject more insulin to overcome their effect. Some women may even require two injections each day. This does not imply anything about the severity of the problem or the outcome of the pregnancy. The goal is to maintain normal blood sugar levels with whatever dosage of insulin is needed.

Can blood sugar level go too low?
Occasionally,  blood sugar level may get too low if one is taking insulin. This can happen if one delays a meal or exercise more than usual, especially at the time insulin is working at its peak. This low blood sugar is called “hypoglycemia” or an “insulin reaction.” This is a medical emergency and should be promptly treated, never ignored.

The symptoms of insulin reaction vary from sweating, shakiness, or dizziness to feeling faint, disoriented, or a tingling sensation. Remember, if taking insulin injections, the patient needs to keep some form of sugar-sweetened candy in her purse, at home, at work, and in the car. In case of an episode of hypoglycemia, she will be prepared to treat it immediately. She should be sure to eat something more substantial afterward. Also, she should report any insulin reactions or high blood sugar levels to her doctor right away in case an adjustment in treatment needs to be made.

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